The ever restless and enterprising Michael Winterbottom has taken on the supposedly unadaptable The Life and Opinions of Tristram Shandy, Gentleman - "a postmodern novel before there was any modernism to be post about", as the star Steve Coogan explains - is one of his best films, and certainly his funniest.

Springy with the same self-reflexive gymnastics of Winterbottom and Coogan's previous collaboration, 24-Hour Party People, A Cock and Bull Story turns Laurence Sterne's 18th-century novel about writing a novel into, naturally, a movie about making a movie. The principals portray both the book's characters and themselves; Coogan does triple duty as himself, Tristram's father, and Tristram, who himself flits in and out of the book's events ("That is a child actor pretending to be me," he explains at one point).

Martin Hardy's spry script plays it remarkably close to the bone - the movie Coogan, for example, has a few public-relations problems regarding his sexual activities, and otherwise juggles costume dilemmas, script meetings, time with his neglected girlfriend (Kelly Macdonald) and their newborn son, a half-hearted dalliance with a cinephilic production assistant (Naomie Harris), and a hot chestnut down his pants. The movie also mines comedy from the scramble and strain of low-budget film-making as cast and crew despair over rushes of an underpopulated battle scene or the producers place a desperate call to Gillian Anderson to save the day. Best of all is Coogan's rapport with Rob Brydon (as himself and Toby Shandy): whether the actors are trading Al Pacino impressions or debating the colour of Brydon's teeth ("Tuscan sunset?" "Pub ceiling?"), they exemplify the film's infectious improvisational energies.